Flash lamps, which are discharge lamps used for laser pumping, can exhibit instable behavior in the short-pulse range (for example, for pulses less than about 0.5 ms). Thus, a correlation between pump light emitted from the flash lamp and the flash lamp current, voltage, or electric pumping power is possible only to a limited degree. The differentiation between stable and instable flash lamp behavior is thereby primarily based on the specific transient oscillation behavior. FIGS. 3a and 3b illustrate this on the basis of two oscilloscope recordings of a conventional prepulse control using the current of the flash lamp, which has previously been used to bring the laser to the laser threshold. FIGS. 3a and 3b show the laser light power Plaser, the pump light power Ppump, and the flash lamp current IB, or the current default ISET (FIG. 4) for the current-controlled lamp current source relative to time. The flash lamp current IB is current-controlled using a ramped current default at the flash lamp current source. When the pulse duration and the pulse power parameters are identical, FIG. 3a shows a relatively faster pump light power increase to the trigger level of the laser (laser threshold power) and FIG. 3b shows a relatively slower increase. In contrast to FIG. 3b, FIG. 3a shows the non-transient first pulse of a pulse sequence, whereas the transient state has been reached in FIG. 3b. 
As is shown in FIG. 4 for a plurality of oscilloscope recordings that are shown on top of each other (where the horizontal scale is time), the differing increase in pump light power produces a trigger jitter Δ of approximately 250 μs, where all oscilloscope recordings are shown being shifted (triggered) to a common laser pulse start. A jitter Δ defines temporal fluctuations/inaccuracies in a clocked process, i.e., the laser pulses are not triggered at identical intervals in the short pulse range, but are delayed or prematurely triggered. An instable transient behavior of the flash lamp causes pulse trigger jitter, since the time intervals vary in which the optical pumping power reaches the laser threshold.